Bacterial infections and the spread of viruses is an ever growing health concern. Numerous ways exist to kill bacteria which require direct contact between an oxidant and the virus or bacteria and many commercial products claim a 99.99% kill rate of these microorganisms. In order to fulfill these claims, these products must contact 99.99% of the target microorganisms. However, achieving direct contact with all of the microorganisms is difficult due first of all to the nature of the materials locations where they are found such as clinging to clothing fibers, utensils, tools, and other common devices having large surface areas with numerous cracks, grooves, and hidden locations for bacteria and viruses to congregate. Furthermore, it has been shown that bacteria cells have a tendency to clump together, thus protecting cells inside the clump from the oxidant resulting in some number of cells that are difficult to kill.
One effective technique for obtaining a satisfactory kill rate of both bacteria and viruses is to immerse the object in ozone gas which disinfects and effectively eliminates the bacteria as well as reducing the advantage gained by the clumping effect. Ozone (O3) is effective because it is a strong oxidant and disinfectant, being more effective than hydrogen peroxide or bleach and iodine, and does not leave any residue or odor. Ozone is naturally occurring and can be used to purify air, water, and some foods. For example, it is used in conjunction with water treatment to rid water of hazardous pathogens including chlorine resistant cryptosporidium and is also used as an alternative disinfectant for water sensitive produce.
Ozone destroys bacteria by interfering with the metabolism of bacterium cells and in sufficient quantities, ozone will break through the cell membrane and lead to the destruction of the bacteria. Ozone also destroys viruses by diffusing through the protein coat resulting in damage to the viral RNA. For example, ozone has been shown to be effective in destroying Methicillin-Resistant Staphylococcus Aureus (MRSA), Shaphylococcus Aureus (Staph) and Candida virus. Kill rates of 99.99% have been demonstrated in these bacteria when exposed ozone for 10 seconds to 8 min. with ozone concentrations between 300 and 1500 ppm.
Thus ozone has proven to be an efficient and effective sanitizing substance capable of killing bacteria and viruses. However, due to the powerful oxidizing properties that make it a strong sanitizing agent, ozone is also a powerful irritant for humans, affecting especially the eyes and respiratory systems and can be hazardous. Even low concentrations of ozone can be harmful to the upper respiratory tract and the lungs. The severity of injury depends on both by the concentration of ozone and the duration of exposure. Therefore, the U.S. Occupational Safety and Health Administration (OSHA) the National Institute of Occupational Safety and Health (NIOSH) have both established exposure limits (PEL) for work environments where ozone is used or where it is likely to be produced.